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No description available.

Device drivers constitute a significant portion of an operating system's source code. The effort to develop a new driver set is a sobering hurdle to the pursuit of novel operating system ventures. A practical solution is to reuse drivers, but this can contradict design goals in a new operating system. We offer a new approach to device-driver reuse, with a focus on promoting novel operating-system construction, which insulates the new operating system from the invariants of the reused drivers, while also addressing development effort. Our solution runs the drivers along with their original operating systems inside virtual machines, with some minor reuse infrastructure added to the driver's operating system to interface with the rest of the system. This approach turns the drivers into de-privileged applications of the new operating system, which separates their architectures and reduces cross-influences, and improves system dependability. Virtual machines help reuse drivers, but they also penalize performance. The known solution for improving virtual machine performance, para-virtualization, modifies the operating system to run on a hypervisor, which has an enormous cost: substantial development effort, and abandonment of many of virtualization's benefits such as modularity. These costs contradict our goals for driver reuse: to reduce development effort, and to easily reuse from a variety of operating systems. Thus we introduce a new approach to constructing virtual machines: pre-virtualization. Our solution combines the performance of para-virtualization with the modularity of traditional virtual machines. We still modify the operating system, but according to a set of principles called soft layering that preserves modularity, and via automation which reduces implementation costs. With pre-virtualization we can easily reuse device drivers. We describe our driver-reuse approach applied to a real system: we run virtual machines on the L4Ka::Pistachio microkernel, with reused Linux drivers. We include an evaluation and demonstrate that we achieve throughput comparable to the native Linux drivers, but with moderately higher CPU and memory utilization. Additionally, we describe how to apply pre-virtualization to multiple hypervisor environments. We include an evaluation of pre-virtualization, and demonstrate that it achieves comparable performance to para-virtualization for both the L4Ka::Pistachio and Xen hypervisors, with modularity.

Thesis (M.S.)--Rochester Institute of Technology, 1983. / Typescript. Includes bibliographical references (leaves 97-101).

Berkeley UNIGRAFIX is a graphics system that runs under the UNIX operating system. It comprises a collection of rendering programs and scene generating programs. Scenes of objects are described in a terse, human-readable format called the UNIGRAFIX descriptive language. In order to display parametric curves and surfaces using UNIGRAFIX, we developed a scene generator called UGTRACE. It traces a set of parametric equations and generates a scene file written in the UNIGRAFIX format. Two tracing modes as well as two displaying modes were designed. The Berkeley UNIGRAFIX system was installed in the McMaster environment. For our purpose, we also modified the various device drivers of UGDISP, the latest version of the renderers. Available output devices include the AED colour graphics terminal, the IMAGEN laser printer and the IBM PC emulating a Tektronix 4010 terminal. UGDISP is used to display scene files generated by UGTRACE. / Thesis / Master of Science (MSc)

El texto completo de este trabajo no está disponible en el Repositorio Académico UPC por restricciones de la casa editorial donde ha sido publicado. / This analysis proposes a decision tree for selecting cross-device communication technologies for iOS and Android mobile devices. This tree accelerates the selection of cross-device technologies by taking into account known use cases of interaction. Five different communication technologies were tested (Real-time Multiplayer, Nearby Messages, PeerJS, iBeacon and Eddystone) by means of 13 proof of concept applications distributed between both operating systems (Android-iOS, iOS-iOS, Android-Android) and the design of 20 architecture diagrams of three types: sequence (connection to services and message sending), deployment and component. The decision tree was validated by mobile development experts resulting in a maximum reduction of up to 30 days of technology selection research. The effectiveness of the tree as a tool is 60%, its usefulness 80% and its ease of comprehension 90%, according to the results obtained from the experts. / Revisión por pares

In the software world, high complexity of a problem solution comes along with a high risk for bugs and vulnerabilities. This correlation is particular perturbing for todays commodity operating systems with their tremendous complexity. The numerous approaches to increase the user’s confidence in the correct functioning of software comprise exhaustive tests, code auditing, static code analysis, and formal verification. Such quality-assurance measures are either rather shallow or they scale badly with increasing complexity. The operating-system design presented in this paper focuses on the root of the problem by providing means to minimize the underlying system complexity for each security-sensitive application individually. On the other hand, we want to enable multiple applications to execute on the system at the same time whereas each application may have different functional requirements from the operating system. Todays operating systems provide a functional superset of the requirements of all applications and thus, violate the principle of minimalism for each single application. We resolve the conflict between the principle of minimalism and the versatility of the operating system by decomposing the operating system into small components and by providing a way to execute those components isolated and independent from each other. Components can be device drivers, protocol stacks such as file systems and network stacks, native applications, and containers for executing legacy software. Each application depends only on the functionality of a bounded set of components that we call application-specific trusted computing base (TCB). If the TCBs of two applications are executed completely isolated and independent from each other, we consider both TCBs as minimal. In practice however, we want to share physical resources between multiple applications without sacrificing their independence. Therefore, the operating-system design has to enable the assignment of physical resources to each application and its TCB to maintain independence from other applications. Furthermore, rather than living in complete isolation, components require to communicate with each other to cooperate. The operating-system design must enable components to create other components and get them to know each other while maintaining isolation from uninvolved parts of the system. First, we narrow our goals and pose our mayor challenges in Section 1. Section 2 introduces our fundamental concepts and protocols that apply to each component in the system. In Section 3, we present the one component that is mandatory part of each TCB, enables the bootstrapping of the system, and provides abstractions for the lowest-level resources. We exercise the composition of the presented mechanisms by the means of process creation in Section 4.

This thesis is part of the European MANY project. The goal of MANY is to provide developers with tools to develop software for multi and many-core hardware platforms. This is the first thesis that is part of MANY at Enea. The thesis aims to provide a knowledge base about software on many-core at the Enea student research group. More than just providing a knowledge base, a part of the thesis is also to port Enea's operating system OSE to Tilera's many-core processor TILEpro64. The thesis shall also investigate the memory hierarchy and interconnection network of the Tilera processor. The knowledge base about software on many-core was constrained to investigating the shared memory model and operating systems for many-core. This was achieved by investigating prominent academic research about operating systems for many-core processors. The conclusion was that a shared memory model does not scale and for the operating system case, operating systems shall be designed with scalability as one of the most important requirements. This thesis has implemented the hardware abstraction layer required to execute a single-core version of OSE on the TILEpro architecture. This was done in three steps. The Tilera hardware and the OSE software platform were investigated. After that, an OSE target port was chosen as reference architecture. Finally, the hardware dependent parts of the reference software were modified. A foundation has been made for future development.

In the software world, high complexity of a problem solution comes along with a high risk for bugs and vulnerabilities. This correlation is particular perturbing for todays commodity operating systems with their tremendous complexity. The numerous approaches to increase the user’s confidence in the correct functioning of software comprise exhaustive tests, code auditing, static code analysis, and formal verification. Such quality-assurance measures are either rather shallow or they scale badly with increasing complexity. The operating-system design presented in this paper focuses on the root of the problem by providing means to minimize the underlying system complexity for each security-sensitive application individually. On the other hand, we want to enable multiple applications to execute on the system at the same time whereas each application may have different functional requirements from the operating system. Todays operating systems provide a functional superset of the requirements of all applications and thus, violate the principle of minimalism for each single application. We resolve the conflict between the principle of minimalism and the versatility of the operating system by decomposing the operating system into small components and by providing a way to execute those components isolated and independent from each other. Components can be device drivers, protocol stacks such as file systems and network stacks, native applications, and containers for executing legacy software. Each application depends only on the functionality of a bounded set of components that we call application-specific trusted computing base (TCB). If the TCBs of two applications are executed completely isolated and independent from each other, we consider both TCBs as minimal. In practice however, we want to share physical resources between multiple applications without sacrificing their independence. Therefore, the operating-system design has to enable the assignment of physical resources to each application and its TCB to maintain independence from other applications. Furthermore, rather than living in complete isolation, components require to communicate with each other to cooperate. The operating-system design must enable components to create other components and get them to know each other while maintaining isolation from uninvolved parts of the system. First, we narrow our goals and pose our mayor challenges in Section 1. Section 2 introduces our fundamental concepts and protocols that apply to each component in the system. In Section 3, we present the one component that is mandatory part of each TCB, enables the bootstrapping of the system, and provides abstractions for the lowest-level resources. We exercise the composition of the presented mechanisms by the means of process creation in Section 4.

Both uppermost open source compilers, GCC and LLVM, are mature enough to link-time optimize large applications. In case of large applications, we must take into account, except standard speed efficiency and memory consumption, different aspects. We focus on size of the code, cold start-up time, etc. Developers of applications often come up with ad-hoc solutions such as Elfhack utility, start-up of an application via a pre-loading utility and dlopen; prelinking and variety of different tools that reorder functions to fit the order of execution. The goal of the thesis is to analyse all existing techniques of optimization, evaluate their efficiency and design new solutions based on the link-time optimization platform. Powered by TCPDF (www.tcpdf.org)